Minnesota HealthSolutions (MHS), iCardiac Technologies, and the Mayo Clinic propose the development and evaluation of an inexpensive diagnostic device (the QTc Meter) to support simplified widespread screening in the primary care environment for both congenital long QT syndrome (LQTS) and acquired/drug induced-LQTS. This grant focuses specifically on the QTc Meter for the early detection of LQTS. Congenital LQTS satisfies several criteria that may make screening worthwhile: LQTS is not rare (1 in 2,000 births), follow-on ECG diagnosis is feasible and ideally complemented by genetic testing, LQTS may cause up to 10% of sudden infant death syndrome (SIDS) as well as many deaths in childhood, adolescence, and early adulthood, and although potentially lethal, LQTS is highly treatable when diagnosed. Further, by stimulating cascade screening, diagnosis of affected infants may also prompt identification of asymptomatic but nevertheless affected family members. A novel QT interval measurement device will be utilized that is suitable for accurate deployment in an inexpensive and easily utilized instrument for the primary care environment.